Housing for gear pumps or motors

ABSTRACT

A section of an extrusion profile constitutes a housing especially for use for accomodating a gear pump or motor. The housing has a substantially cylindrical outer contour and a substantially oval cross section and an inner chamber which constitutes at least one longitudinal cylinder having at least one open end and surface lines which extend parallel with the surface lines of the outer contour and perpendicular to the original line threads or flow lines of the extrusion profile section so as to improve the fatigue resistance and especially the tensile fatigue resistance of the housing.

O Unlted States Patent 1151 3,661,480 Forschner et al. [4 1 May 9, 1972 HOUSING FOR GEAR PUMPS OR 1 References Cited MOTORS UNITED STATES PATENTS 1 Inventors Friedrich Fiimhn"; Hans Kunhfls, both 3,133,506 5/1964 Luciani ..4l8/206 of walblmgen; Karl-Heinz Mull", Gerlm- 3,376,824 4/1968 Turolla ..4l8/206 8 Germany 3,463,089 8/1969 Newborough ..4l8/l79 [73] Assignee: Robert Bosch Gmbll, Stuttgart, Germany Primary Examiner-Carlton R. Croyle [22] filed: Assislan! Examiner-John J. Vrabuk [2| 1 Appl' 889,280 At!0rneyMichael S. Striker 57 ABSTRACT [30] Foreign Application Priority Data l A section of an extrusion profile constitutes a housing espe- Jan. 16, l969 Germany ..P 19 01 964.8 ciauy for use for accomodating a gear pump or motor The housing has a substantially cylindrical outer contour and a [52] Cl substantially oval cross section and an inner chamber which l 264/155 constitutes at least one longitudinal cylinder having at least 1 Int Cl B23 15/00 Bzlc 23/00 F010 1/18 one open end and surface lines which extend parallel with the [58] Fieid p 218/179 206 270 surface lines of the outer contour and perpendicular to the original line threads or flow lines of the extrusion profile section so as to improve the fatigue resistance and especially the tensile fatigue resistance of the housing.

9 Claims, 3 Drawing Figures HOUSING FOR GEAR PUMPS OR MOTORS BACKGROUND OF THE INVENTION The present invention relates; to a housing especially adapted for accommodating a gear pump or gear motor, and a method of manufacturing such a housing, the latter being made from a section of an extrusion profile and having, in essence, a cylindrical outer contour and, in particular, an oval cross section, and being formed with an inner chamber constituting at least one longitudinal cylinder with at least one open end and surface lines extending in parallelism with the surface lines of the outer contour.

Already known in the art is a housing made from an aluminum alloy and used for accommodating a gear pump or a gear motor and is made as an unfinished casting from a section of an extrusion profile. This housing has an inner chamber constituted by two, each other partly overlapping circularcylindrical bores, with the surface lines ofthe inner chamber extending in parallelism with the original line threads or flow lines of the section of the extrusion profile.

This housing which, during operation of the pump or motor, is subject to a strong continuous load of interval pressure, has the disadvantage that the greatest load of tensile stress is applied transversely to the direction of flow in the structure.

Hitherto, it has not been realized that the transverse resistance values" of the structure are less than the longitudinal resistance values" of the same, in particular as regards the fatigue resistance pattern or behavior.

SUMMARY OF THE INVENTION Object of the present invention is to provide a housing especially for use for accommodating a gear pump or a gear motor and which, compared with conventional housings of such type and with the same material expenditure, has a considerably increased fatigue resistance, in particular the tensile fatigue resistance.

According to the invention this is accomplished by arranging the surface lines of the inner chamber of the housing such that they extend perpendicular relative to the original line threads or flow lines of the extrusion profile section from which the housing is made.

This has the advantage that the tensile stresses resulting from the load of internal pressure in the housing, in each case extend in direction parallel with the flow through the housing, i.e., parallel with the line threads of the extrusion profile section. This enables to increase the fatigue resistance of the housing without reducing the wall strength of the same.

It is of particular noted advantage that the original line threads are flow lines of the extrusion profile section extend in direction of one of the main axes of the curve which bounds the cross section of the housing, in particular the novel cross section of the housing according to the invention.

Such a housing according to the invention is manufactured by producing the outer contour of the housing in a noncutting conventional pressing or molding device and with the pressing or molding direction oriented perpendicular to the original line threads or flow lines of the extrusion profile section.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved housing itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a final pressed housing according to the present invention;

FIG. 2 shows a further embodiment of a further housing according to thepresent invention; and

FIG. 3 shows a section of a blank of an extrusion profile from which the respective housings of FIGS. 1 and 2 are formed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Provided in the overlapping region of the bores 3 and 4, are

two convex transition faces which tangentially merge into the walls of the bores. The outer contour of the housing 1, in cross section, is substantially oval, and the straight major-lateral surfaces of the housing are provided with outwardly projecting flange portions 5, 6. Seen in cross-sectional view, both ends of the flange portions 5, 6 are provided with convex transition faces.

The housing 1 is seen to comprise the schematically shown line-threads 7 which originate from the border zones of the heterogeneities of the (former) cast center of the structure. The line threads 7 in the finished housing I, extend in direction of the empirically formed maximum tensile stressesa Z max I,illustrated by the double arrow and which-occur during operation of the pump or motor.

These tensile stressesyvhich are oriented parallel with the main center axis 9 of the cross-sectional surface of the housing, originate as a result of the strong internal pressure strain to which the housing, during its operation, subjected. The line threads 7 are slightly bent toward the main axis 9 in the region of the two rounded minor surfaces 10, 11.

This pattern of the line threads 7 results from the reshaping process by which the outer contour of the housing I is constituted.

A further embodiment of the present invention is shown in FIG. 2. The shape of the housing 11 is similar to that of FIG. 1, however, the individual dimensions of the respective lines have an inter relationship which is different from their counterparts shown in FIG. I.

Shown in FIG. 2 are the line threads 17 whose main direction, in this embodiment, is parallel with the minor center axis 19.

With this housing, likewise adapted for machine types incorporating gear wheels and the like, it has been found that the maximum tensile stresses (72 max 2, illustrated by the double arrow 18 and occuring during operation of the pump or motor, extend in direction of the minor center axis 19.

It will be self-evident that the mode of application of the present invention is not limited to the exact configuration of the outer contour of the housing or of the inner chamber of the same.

Shown in FIG. 3 is a blank 20 which is used for the manufacture of the respective housings shown in FIGS. 1, 2, and which is cut from a strand of extrusion profile at a desired length.

The schematically shown line threads 24 extend in direction in which the strand is extruded.

In order to form the housing shown in FIG. I, the blank 20 is introduced into a desired and conventionally constituted matrix, not shown, in such a manner that the line threads are oriented in a required direction.

The inner chamber 2 of the housing of FIG. 1 is then formed, without cutting, by applying and pressing with a punch which has a cross section corresponding to that of the inner chamber 2. The excess material is pressed outwardly such that the originally rectangular blank is formed with the two round minor surfaces 10, 11 and the transition surfaces between the two flange portions 5 and 6.

In order to form the housing shown in FIG. 2, the blank 20 is introduced into the matrix with the line threads 24 extending in the required direction, upon which the punch is again perpendicularly applied to the upper surface and the original line threads in the blank and is compelled to form the inner chamber 2 and thereby the outer contour of the housing.

In certain instances it may be purposeful, for example, for technical or production reasons, to initially manufacture the housing in solid condition, i.e., without the inner chamber 2. To this end, first the pressing of the outer contour of the housing isinitiated and effected in a conventional matrix with the extrusion profile section and the line threads 24 embedded therein, oriented in the desired direction.

The pressing step proceeds and is directed in a .direction perpendicular to the original line threads 24 of the extrusion profile. V Y

Subsequently, and in a further processing step, the inner chamber 2 is then machined in the solid housing blank.

Instead of utilizing the hereinbefore mentioned aluminum alloy, also other suitable forgeable and pressable materials may be used.

lt will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of housings used for gear pumps and motors differing from the types described above.

While the invention has been illustrated and described as embodied in the housing according to the invention, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will sofully reveal the gist of the present invention, that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention, and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. An article of manufacture, a housing particularly for gear pumps or gear motors, said housing comprising a metal shell having an internal flow line structure in which the flow lines extend substantially in one direction, said shell having. an outer peripheral surface and an inner peripheral surface bounding an inner cavity of said housing and open at least at one end thereof, the generatrices of said surfaces extending transversely to said flow lines.

2. A novel articleas defined in claim 1, wherein said inner cavity comprises a substantially cylindrical surface of non-circular cross section having a major and a minor axis with one of said axes coincident with the original direction of said flow lines.

3. A novel article as defined in claim 2, wherein said one axis is the major axis.

4. A novel article as defined in claim 2, wherein said one axis is the minor axis.

5. A novel article as defined in claim 2, wherein said cross section of said housing is substantially oval.

6. A method of making a housing, particularly for gear pumps or gear motors, comprising the steps of, extruding an elongated bar of material characteristic; forming in said bar an interval cavity having an inner peripheral surface, and forming at the exterior of said bar an outer peripheral surface of desiredcontour, with the generatrices of both of said surfaces extending transversely to the elongation of said bar and thereby to the original direction of extrusion of said bar.

7. A method as defined in claim 6, wherein the step of forming said outer peripheral surface comprises exerting pressure on the outer side of said bar in direction normal to said elongation to thereby deform the material of said bar to the shape of the desired outer peripheral surface.

8. A method as defined in claim 7, wherein said inner cavity is formed by removing material.

9. A method as defined in claim 7, wherein said inner cavity is formed by pressure-displacing material. 

1. An article of manufacture, a housing particularly for gear pumps or gear motors, said housing comprising a metal shell having an internal flow line structure in which the flow lines extend substantially in one direction, said shell having an outer peripheral surface and an inner peripheral surface bounding an inner cavity of said housing and open at least at one end thereof, the generatrices of said surfaces extending transversely to said flow lines.
 2. A novel article as defined in claim 1, wherein said inner cavity comprises a substantially cylindrical surface of non-circular cross section having a major and a minor axis with one of said axes coincident with the original direction of said flow lines.
 3. A novel article as defined in claim 2, wherein said one axis is the major axis.
 4. A novel article as defined in claim 2, wherein said one axis is the minor axis.
 5. A novel article as defined in claim 2, wherein said cross section of said housing is substantially oval.
 6. A method of making a housing, particularly for gear pumps or gear motors, comprising the steps of, extruding an elongated bar of material characteristic; forming in said bar an interval cavity having an inner peripheral surface, and forming at the exterior of said bar an outer peripheral surface of desired contour, with the generatrices of both of said surfaces extending transversely to the elongation of said bar and thereby to the original direction of extrusion of said bar.
 7. A method as defined in claim 6, wherein the step of forming said outer peripheral surface comprises exerting pressure on the outer side of said bar in direction normal to said elongation to thereby deform the material of said bar to the shape of the desired outer peripheral surface.
 8. A method as defined in claim 7, wherein said inner cavity is formed by removing material.
 9. A method as defined in claim 7, wherein said inner cavity is formed by pressure-displacing material. 